the Slide for second class with our Android Course. Revise the lesson then do the homework everyone who joined this class =)

1. Android platform
Activity
Cao Minh Vu
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cmv.ict@gmail.com

2. Outline
 What is activity
 Starting activity
 Shutting down activity
 Activity lifecycle
 Save state
 Back stack
 Tips
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3. What is activity
 An application component
 A screen with which user can interact
 A window to draw its UI
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4. Creating an activity
 Declare in manifest.xml
 Implement xml layout (optional)
 Extends from Activity
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5. Starting an activity
 By name
Intent intent = new Intent(this, SignInActivity.class);
startActivity(intent);
 By action
Intent intent = new Intent(“com.multi.action_show”);
startActivity(intent);
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6. Starting an activity (cont)
 Start for result
Intent intent = new Intent((Intent.ACTION_PICK);
intent.setType(“video/*”);
startActivityForResult(intent, requestCode);
protected void onActivityResult(int requestCode, int
resultCode, Intent data) {
}
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7. Shutting down an activity
 Explicitly
 Finish();
 Implicitly
 Let the system do it (when user press BACK HW)
 Force Close
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8. Activity lifecycle
 onCreate(Bundle savedInstanceState)
 initialize the essential components
 setContentView();
 onResume()
 just before the activity starts interacting with the
user (foreground)
 OnPause()
 Another activity is in the foreground + focus, but this
one is still visible => completely alive
 partially transparent or doesn't cover the entire 8
screen

9. Activity lifecycle (cont)
 OnStop()
 completely obscured by another activity
(=>background)
 is not attached to the window manager
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10. Activity lifecycle (cont)
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11. Save state
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12. Back stack
 Android Manifest
 "standard" (the default mode)
 "singleTop"
 "singleTask"
 "singleInstance"
 Flag
 FLAG_ACTIVITY_NEW_TASK (single task)
 FLAG_ACTIVITY_SINGLE_TOP (single top)
 FLAG_ACTIVITY_CLEAR_TOP
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13. Configuration change
 Screen orientation, change language...
 Call onDestroy and onCreate()
 Avoid ?
<activity android:name=".CustomGalleryActivity"
android:configChanges="keyboardHidden|
orientation"/>
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14. Homework
 Given activities started in order: A->B-C->D
Draw the back stack to illustrate 2 cases:
 1. Start new activity D
 2. Start new activity B
with modes: standard, singleTop, singleTask,
singleInstance and Flag:
FLAG_ACTIVITY_NEW_TASK,
FLAG_ACTIVITY_SINGLE_TOP,
FLAG_ACTIVITY_CLEAR_TOP
Requirement:
 Draw back stack state when start new activity and
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then press back HW until the program is closed

15. Tips
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16. Reference
 http://developer.android.com/guide/topics/funda
mentals/activities.html
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